I get several questions a week from readers with cars that won’t start. Some have an idea of what might be the problem—like a dead or weak battery—but most don’t have any idea where to start to pinpoint the root cause. But before I get into how to diagnose a no-start issue, I do have to ask some seemingly silly questions. I have seen many, many customers pay huge towing bills for these causes, so let’s just rule them out right away:

Verify that your car is in Park. The car will only start in Neutral or Park.

If you have an anti-theft device, make sure it isn’t malfunctioning.

If the key won’t turn at all, your tires might in a bind against the curb, or the car may have rolled back a bit after you put it in Park. If this happens, try jerking the steering wheel to the right to release it, or you may need to physically rock the car to get the key to release.

If you don’t have any of these problems, you are unfortunately in a real no-start scenario. So here’s some basic information on how to troubleshoot your starter, alternator, and battery.

The three components required to get that engine started and keep it running are 1) a spark that ignites the fuel, 2) the fuel, and 3) compression—the process the engine uses to combine the spark and the fuel. So to diagnose your car, we have to systematically go through each of the processes your car uses for these components until we can find your problem.

First, let’s pay more attention to what happened and didn’t happen when you tried to start the car. Did you turn the key and absolutely nothing happened? Maybe a clicking noise or no noise at all? Did the engine try to turn over but just couldn’t make it happen? And maybe the radio and lights were still able to function, or maybe they didn’t have any power either.

If the lights are dim or completely dead, concentrate on the battery and its connections. If your headlights are functioning and still fairly bright, you can probably assume that your battery still has a lot of juice and is working properly. In this case, we now move to the starter.

Here’s what the starter does: When you turn the key, the battery feeds electricity to the starter, which starts turning over the engine. (The starter will only engage while the key is turned all the way on. As soon as you let off on the key, the starter disengages.) As the starter provides this movement within the engine, the pistons start pumping up and down inside a cylinder, which creates and releases compression within that cylinder. That compression causes a small explosion within the confined cylinder of the engine, and this reaction is what generates the engine’s horsepower.

What a broken timing belt or timing chain sounds like if your car won’t start

So if the headlights are bright but nothing happens when you turn the key, you probably have a problem with the starter or the connection from the battery to the starter. Common problems in this area are a bad ground connection and either burned or damaged wiring.

When you turn the key and you hear the engine turning over, your starter is working. Of course, if you continue to try to start the car unsuccessfully, you can drain the battery in these attempts until the starter doesn’t have enough juice to even try any more, but that doesn’t mean that the starter isn’t working properly.

If the battery and the starter seem to be functioning properly, the next step is to check for fuel. Yes, customers really do have their cars towed in because they won’t start, and the only thing we have to do is to put gas in the empty tank. Verify that the car has fuel and the fuel gauge is working, then try to determine if you are getting fuel compression in the engine.

Pay close attention to the engine sound—Is it turning all the way over? Is it turning over too slow or too fast? A broken timing chain or timing belt will cause the engine to turn over very easy and fast because the compression process is not happening.

When you turn the key to the ON position and don’t hear a slight buzzing noise under the hood, there may not be power to your fuel pump or your fuel pump may not be working. And even if it is working, there may not be enough fuel pressure to start the car. If your mechanic suspects this is the problem, he can use a fuel pressure gauge to test this component. And yes, by this point, you are probably going to need to go to the mechanic.

More than likely, you’ve already noticed that as we go down this list, the diagnostics and probable problems are getting more complicated. Now we need to determine of the spark component is your problem, and this process can be even more tricky to test. You will need experience and the proper tools to work on spark issues, so this is also a job for your mechanic.

If you are at the stage that you need to call in expertise to fix your car, you have at least saved yourself and the mechanic time and effort ruling out the battery, starter, and empty fuel tank. Not only does he not have to guess what happened, but hopefully you have found the problem yourself.

If it’s time for professional intervention, call your mechanic and use what you have gained to relay specific no-start information. Saving him time to diagnostics can often save you money, and will always save both of you time and hassle.

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Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."

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Christina Blue

I have a 2000 Ford Taurus and I’m having problems with it starting. Sometimes it starts and sometimes it wont when it does it runs great. I have had the battery tested and alternator tested both come back fine but for my car to start I have to have someone jump me and when they do it starts right up and runs fine. I’ve checked wires, connections and I’m lost at this point can you help me

Ethan Wiggins

i need help how do i remove a prolock security sytem on a 92 dodge diesel truck

Austin Davis

Thanks Chad. I would first try a new or alternate ignition key, the key chip wears out over time. If that does not do it, the ignition lock cylinder (part the key goes into) might be worn out and need replacement. Worst case scenario the BCM (body control module) might have a problem and need replacement…rare, but I have seen them fail and cause issues like this.

I wanted to thank you for the article. I assumed my issue was my battery. The place said it was keeping a charge, but the cranking power was low. I had just replaced another battery with the same issue so I bought it.

I installed it and had the same results. Well, I could have gotten more time out of my original battery, but not much I suspect.

So the issue ended up being the Passlock® passive theft deterrent system. I have a 2002 Pontiac Grand Am and it along with other GM models have this system. It does some checks and if it isn’t satisfied it won’t send fuel to the engine. (Problem #1!)

I could tell this was my problem by seeing the “Security” red light blink on and off after I tried to start and put the key in the and tried to start it and then let it go back to the “On” position.

I had to wait about 10 minutes for the Security light to go out. I then turned the key to “Off” for about 5 seconds. Then I tried to start it again … and it worked.

Now, I assume that some piece is going bad and I’ll have to replace it. But for now, I’m able to get my car started.

Again, thanks for the post. Hopefully this comment may help someone else. More detail about this issue is found at the bergerweb (dot) net website. He lists some models that this affects. People should be able to tell if the Security light blinks at them (or stays on) after trying to start the car.

Austin Davis

Does this vehicle have a MAF sensor (mass Air Flow) located in the fresh air duct before the air filter, usually toward the front of the vehicle. Large round Sensor with wires before the air cleaner. If so, try unplugging it and see if the engine starts and stays running, you can sometimes bang on it lightly with your hand as someone cranks the engine over.

debbie stanford

eb falcon hard to start and wont stay running but wheb it does go will run for 5-10 seconds and conk out have changed the spark plugs, fuel filter tested fuel pump have changed fuel pressure regulator and o2 sencor tested MAP sencor i hope you can help me with this problem as we cannot seem to get the car going thank you

Austin Davis

I would start with checking the fuel pressure AT the engine using a manual fuel pressure gauge.

jeff

question nobody been able to fix my car
1997 ford contour 2.0l fi cranks won’t stay running starts and dies with pedal on the floor and pops in throttle body not like back fire like burb

Austin Davis

Hi there, thanks for the kind words!

My first thought is to change the battery with a new one or a known good battery and see what happens. I am hoping either a weak internal battery cell or a bad connection at the battery cables is causing your problems.

If you still have troubles, let me know and we can start ruling things out.

BTW, we home school our children ( I see your email address :))

God Bless you too
Austin

Miss M

Hi! Thank you for this article! Unfortunately, I find myself somewhat between a couple of the symptoms.

I have a 1990 Mercury Villager Sport. Recently, we’ve had some trouble starting it, but have had to jump it only once.

I am familiar with the full, very audible, “Rar-rar- rar-rar” sound that a car will give when it is turning over but not starting. This is somewhat different, or at least I think it is.

Usually, it will start up after a split-second pause. When it doesn’t, I hear this quiet “sh-sh”, long pause, “sh-sh” (like the pulleys and belts moving quietly for a moment every few seconds). If I keep the key turned, it will continue this, and then eventually, suddenly, without explanation, it will start… but somewhat weakly. Depressing the gas helps bring it to a more normal running level.

Driving it, we have sometimes dared to use the A/C (turning it on a few minutes after starting), as it is very hot right now. I noticed today that sometimes the fan speed varied with the speed of the car — or with whether I had my foot on the brake or accelerator. The engine seemed abnormally quiet when I had to stop to turn, as well, but it has not stalled.

If I am not imposing too much, can you give me any idea which part is failing? I know a dying battery can give some strange symptoms sometimes, but I’m just not sure what to think of this.

Thank you in advance for any direction you can give me, and God bless you!

Austin Davis

Grate, thanks for your comment. Glad it was helpful and hope you learned something new.

Vanessa R

Thank you very much, it is good to know what the car needs to start and what to check before calling the mechanic, usually it is a mystery to me when my car does that.

Austin Davis

Glad to help, thanks for your comment

Boe jankins

Thank you very much. This site is very helpful!

Austin Davis

Sounds like either a bad starter motor (drive gear on the end of the starter is not engaging the flywheel) or you have a worn out flywheel that is missing teeth that the starter motor is trying to turn…so the starter just free spins.

Easiest thing is to replace the starter motor and inspect the flywheel for any missing teeth.

Boe jankins

I have just put a new battery into my 68 f100 pickup. But when I turn the key, it only makes a whirring sound with no engine movement. What could be the problem?

Austin Davis

Thank you very much! God Bless You Too!

saldy(philippines)

your site is very comprehensive so easy to understand.
I’ll try it with my nissan bx type 90 model.